Topology

Topology is about how the vertices and edges are placed to create the surface of the mesh, the topology is rather important in animation concretely in human mesh; it is a key aspect on modelling. Meshes created will be animated and our goal is to obtain realistic expressions, we can achieve fast framerates and good deformation with a good topology. We will see un-natural expressions with a bad topology, faces deformed in the shape grid, broken structure in muscles and many other strange visual effects.

In order to identify good and bad singularities I’m going to analyse animated and static examples. We can see a good example of bad topology with a mouth animation in next picture; the character is speaking, its topology is generating a strange effect at the end of the mouth, something like a membrane, it is not a real topology of human mouth.

Click on image to see animation

Here we can see how the problem is fixed, it is a new face mesh even with less faces, a better topology in the mouth than the last one, when the face mesh is speaking we can see a realistic effect on mouth.

Click on image to see animation

Last example demonstrates we can build a model with less faces, less geometry but still looks realistic and accurate. Topology is not based on the amount of polygons, topology based on the major wrinkles which formed by muscles. We can see how to draw edges on the face based on those wrinkles which give the mesh a good topology.

Wrinkles

Next, topology could have a lot of complexity zones but when we study the human body we can separate in different zones such as head, body, extremities and shoulders; concrete case the head have much more screen time than other parts, it’s a characteristic of human, and we will see gestures, expressions and feelings than other parts can’t show us. In the next link we can see good examples of animation with good topology for the body and extremities; we noticed that muscles movements are the most important in the cinematics.

Therefore, we can deduce some key aspects of topology, one of them is that we don’t need unnecessary faces in edge loop, triangle, poles, we need to avoid poles although sometimes it’s impossible to do, we can see that in next picture.

Poles

There is no looping structure in human face but we can model that for obtain a simplistic polygon topology.

Good topology can be achieved by creating quad faces because triangle faces will not deform the mesh correctly; that polygons should always be as square as we can, no long thin or diamond shaped.

Besides, topology is very important because model a character or an animated object is not only create a massive polygonal mesh to simulate the reality, we have to see the movements that will have and what are the key points, polygonal parts that will interact in those movement in order to do a good rigging. Another important aspect to do good topologies is the fact of re-use the same model to create more based on the first one, we can create a general topology of head or body and lately just do little changes to adapt the appearance to the new character or object. For example, MakeHuman is an open source project with that idea, you can download software that provides you with a unique mesh which you can change completely only with simple modifiers.

Finally, I have to identify complexity zones in my own model. As I said in first post my character will be a woman so the majority of the complexity zones will be in face and extremities because she’s going to be a real human body. I will focus all my efforts to create a good mesh with a good topology, especially in extremities, because she will jump, run and I would like to see realistic movements. The plan in terms of topology is researching as far as I can to learn with good topologies and try to imitate same key aspects. I’ve thought to see some drawing books about human anatomy and human drawing; it could be interesting as well as start looking 3D models and meshes in next interesting link.

Topology research

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